Objective To investigate the influence of changes in blood flow parameters on pulse rate characteristics by taking the advantage of controllable parameters in an experimental cardiopulmonary bypass system.Methods A set of human circulatory system equipped with an in vitro wrist model was established.By changing parameters such as the heart rate,wrist flow,pressure,and system compliance,a photoplethysmography pulse wave signal was obtained from the wrist model,and the time-and frequency-domain indices of pulse rate variability were extracted.Results Changes in heart rate,pressure,and system compliance caused a change in pulse shape,but the time domain indices NN50 and PNN50,which indicate pulse rate variability,were zero,and the other indices and frequency domain indices were in the very low value category.Conclusions In the absence of heart rate variability,hemodynamic changes in heart rate,wrist flow,blood pressure,and system compliance did not produce significant pulse rate variability.This study can provide a reference for studies on pulse rate variability and heart rate using more convenient wrist acquisition equipment.

Objective To investigate the effect of different coating methods on production quality of complex and flexible silicone vascular replicas. Methods Based on models of anterior communicating artery aneurysms, several patient-specific models were made by using spray-coating method and brush-spin-coating method respectively, and two methods for making the same vascular structure were quantitatively compared in terms of thickness growth, circumferential uniformity and light transmittance. Results Brush-spin-coating method was better than spray-coating method in the thickness control and coating uniformity for fabrication of vessels with large curvature, variable diameter and straight tube, and the model had preferably light transmittance and surface smoothness. The relative deviation of thickness by brush-spin-coating method was decreased by 8. 9% , 10. 8% and 16. 9% respectively compared with spray-coating method. Conclusions At present stage, the brush-spin coating method has the advantage of thickness uniformity and light transmittance over the spray-coating method in making silicone phantoms, and it has promising application prospects in fluid mechanics field of in vitro experiment on large vessels.